Rotary kiln



March l?, 1936. C. s. GLENN ROTARY KILN FiledV May 27, 1935 2 Sheets-Sheet l INVENTOR dr/e5 .5f 7e/7n ATTORNEYS March 7, 1936. c. s. GLENN 2,034,80

ROTARY KILN Filed May 27, 1935 2 Sheets-Shes?I 2 INVENTOR (bar/es .S G/ew/v BY p IQQAMW CWNA? ATTORNEYS Patented Mar. 17, 1936 UNITED STATE ROTARY KILN Charles S. Glenn, Syracuse, N. Y., assignorto The Mathieson Alkali Works, Inc., New York, N. Y., a corporation of Virginia Application May 27,1935, serial No. 23,657

1 Claim. v(Cl. 263-33) This invention relates to improvements in ro.- tary kilns with countercurrent ring. The accompanying drawings illustrate a rotary kiln embodying the invention. With the exception of the parts numbered I2, I3 and I4, the rotary kiln illustrated is of conventional construction.

In the conventional rotary kiln with countercurrent firing, as arranged for the calcination of limestone or other calcareous carbonate to proio duce lime for example, the kiln proper is inclined so that rotation of the kiln carries the solids moving thro-ugh the kiln to the lower end from which they are discharged and at which end the kiln is fired. In the usual conventional construction, l5 the lower end of the kiln proper extends into a ring hood within which a bridge wall is arranged transversely of the axis of rotation of the kiln proper, solids being discharged on the side of the bridge wall facing the kiln proper and com- 20 bustion air being supplied to the firing hood on the other side of the bridge wall. In the rotary kiln illustrated in the accompanying drawings, the lower end of the kiln is designated 5, the firing hood is designated 6, the bridge wall is des- 25 ignated l, the discharge chute for solids is designated 8 and the duct for supplying combustion air is designated 9. In this conventional construction, dust or fines tend to accumulate in the space within the ring hood on the hood side of the 30 bridge wall. Such accumulations have been limited to prevent direct interference with the kiln operation by pushing accumulating dust or fines over the bridge wall o-r by pulling it out through ports in the hood by means of slicing bars and rabbles manually worked through ports in the hood. The extra labor, the dilution of the kiln gases with atmospheric nitrogen, the admission of cool and usually excess air, and the contamination of the atmosphere adjacent the firing end regarded as necessary evils. Such accumulations of dust or fines, easily suspended in the gases moving through the kiln, further, provide a supply of such dust or nes in a region such that it 45 tends to build up an increasing concentration of such dust or nes in the combustion zone, the dust or fines moving in a cycle of progressively increasing concentration from the kiln proper into the ring hood and back into the kiln proper 50 and so on. This concentration of dust or fines in the gases of combustion within the iiring hood and at the firing end of the kiln proper frequently reaches a point interfering with the efficiency of the kiln operation and the regularity of the 55 kiln operation.

of the kiln involved in this procedure have beenv I have found that important improvements in eiflciency of operation and regularity of operation of rotary kilns of this construction are to be attained by providing means facilitating the discharge oi dust or fines from the space on the 5 hood side of the bridge wall so that accumulations of dust or fines in this region can be limited not only to an extent sufficient to eliminate the manual operations previously mentioned but also to prevent such accumulations as tend to 101 produce those concentrations of suspended dust or fines in the combustion gases in the iiring hood and in the firing end of the kiln proper interfering with the efficiency and regularity of the operation. A particularly advantageous embodiment of such means is illustrated in the accompanying drawings in which Fig. 1 is a fragmentary vertical section transverse to the axis of rotation o-f the kiln proper through the firing hood between the bridge wall and the lower end of the kiln proper of a kiln embodying my invention, Fig. 2 is a fragmentary vertical section parallel to that illustrated in Fig. l through the firing hood on the other side of the bridge wall, Fig. 3

is a fragmentary vertical section of the firing hood and lower end of the kiln proper through the axis of rotation of the kiln proper and Fig. 4

is a fragmentary elevation parallel to the section illustrated in Fig. 3.

In the rotary kiln illustrated in the accompanying drawings, the lower end 5 of the kiln proper extends into the ring hood 6 through a conventional seal I0. A bridge wall 1 is arranged transversely of the axis of rotation of the kiln proper across the interior of the ring hood and spaced from the lower end of the kiln proper.

A burner for whatever fuel or 'combination of fuels is used in firing the kiln opens into the firing hood 6 through port I I. Solids moving out of the lower end of the kiln proper drop into the 40 space between the lower end of the kiln proper and the bridge wall I and are discharged through chute 8. Combustion air, or other combustion supporting gas, enters the firing hood through duct 9 opening into the space on the hood side of the bridge wall 1. The kiln structure so far described in this paragraph is a conventional construction. Referring particularly to Fig. 2, in such conventional construction, however, a solid oor extends across the space constituting the opening into the hopper I2 and it is particularly in the space above such floor and between the bridge wall and the end of the hood that dust or fines accumulate in conventional construction of this type. 5

In accordance with this invention, however, I provide a hopper I2 beneath and opening into the space on the hood side of the bridge wall 'I so proportioned that a minimum of horizontal Vsurfaces upon which dust or fines might tend to accumulate is left within this region in the firing hood and, in 'conjunction with this hopper, I provide appropriate discharge means I3 to permit discharge` of"l dust or nes collecting in the hopper either continuously or at intervals such that any tendency toward increase in concentration of dust or fines suspended in the combustion gases in the ring hood and in the lower en'd'o'f the kiln proper is avoided. In the particular con-V struction illustrated in the'accompany'ing.l draw'- ings, the lower end of theY discharge means I3' is closed by a manually operated slide gate I4. The rate of collection of dust or fines-in the'hopper I2 in particular instances will determine the na-l ture of the means appropriate for discharge of dust or rfinesA from this hopper.

'I'hechuteA 8 andv the duct 9 may communicate, for example, with any suitable means for preheating the combustion air by heatexchange'with the hot solids discharged fromthe rotary kiln. This invention is of special value and application in connection with installationsV including heat exchange-means for this purpose the operation-of which tends to resuspend in the 'combustion air passing to the firing hood dust or nes leaving the more effective heat exchangers might otherwise be subject.

I claim:`

In rotary kilns' with countercurrent ring in which the lower end of the kiln proper extends into arring hood within which a bridge wall is arranged transversely ofthe axis of rotation of the kiln proper dividing the lower part of the hoodr into aspace through which. solids are discharged'and a space through whichjcombustion' air'enters, the improvement which'comprises a hopper beneath and' opening into' the space through whichcombustion air enters'in'cluding means for discharging dust or fines collecting. therein so` proportioned as to.' minimize' horizontal surfaces in theY space on the hood side ofV the bridgeA wall'.

CHARLESJS. GLENN.` 

